title: Platycodi radix saponin inhibits α-glucosidase in vitro and modulates hepatic glucose-regulating enzyme activities in C57BL/KsJ-db/db mice.
abstract: This study investigated anti-diabetic activity of a concentrated saponin fraction from Platycodi radix (SK1) in C57BL/KsJ-db/db mice and its underlying mechanism. Mice were fed diet with 0.5 % SK1 (w/w) for 6 weeks. SK1 significantly lowered the blood glucose and glycosylated hemoglobin levels and improved glucose and insulin tolerance. The plasma and pancreatic insulin and C-peptide levels and fecal cholesterol content were increased, whereas plasma urea nitrogen, free fatty acid and triglyceride levels were decreased by SK1 supplementation. Glucokinase (GK) activity in the liver was significantly higher in the SK1 group than the control group, whereas the glucose-6-phosphatase (G6Pase) activity was lower. SK1 significantly down-regulated GK mRNA expression compared to the control group but did not affect G6Pase and glucose transporter 2 mRNA. Phosphoenolpyruvate carboxykinase activity and mRNA levels did not differ between groups. SK1 also markedly inhibited the small intestinal disaccharidases activities compared to those of control db/db mice. Furthermore, SK1 was a more effective α-glucosidase inhibitor than acarbose in vitro. Overall, these findings suggest that SK1 is a potential glucose-lowering agent that functions via inhibition of carbohydrate digestive enzyme activities and modulation of glucose-regulating enzyme activities in db/db mice.
authors.affiliation: Department of Food and Nutrition, Sunchon National University, 255 Jungang-ro, Suncheon, Jeonnam, 540-950, Korea.
authors.forename: Jeom-Sook
authors.initials: JS
authors.lastname: Lee
authors.forename: Myung-Sook
authors.initials: MS
authors.lastname: Choi
authors.forename: Kown-Il
authors.initials: KI
authors.lastname: Seo
authors.forename: Jin
authors.initials: J
authors.lastname: Lee
authors.forename: Hae-In
authors.initials: HI
authors.lastname: Lee
authors.forename: Ju-Hye
authors.initials: JH
authors.lastname: Lee
authors.forename: Myung-Joo
authors.initials: MJ
authors.lastname: Kim
authors.forename: Mi-Kyung
authors.initials: MK
authors.lastname: Lee
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology; D065089:Glycoside Hydrolase Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018517:Plant Roots; D031238:Platycodon; D011897:Random Allocation; D012503:Saponins / Q000302:isolation & purification / Q000494:pharmacology*; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D010936:Plant Extracts; D012503:Saponins; D000520:alpha-Glucosidases